Women's Health Matters

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Medical Description

How Your Bladder Works

Continence depends on the normal functioning of the bladder, urethra, sphincters and pelvic floor muscles.

The position of the bladderYour bladder is a hollow muscle, much like a balloon, located behind your pelvic bone and below your belly button. When full, the bladder can hold as much as half a litre of urine. The detrusor is a thick, smooth muscle in the wall of the bladder. It is relaxed and expands as the bladder fills with urine. It contracts and tightens to empty the bladder when you urinate.

At the neck of the bladder is the urethra, a thin tube that leads from the bladder to the outside of the body. In women the urethra is about 1.5 inches long and is located in front of the vagina. The opening of the urethra is called the meatus and is located between the clitoris and the vaginal opening.

Urine is stored in the bladder until it is passed through the urethra and out of the body. Two structures at the neck of the bladder, called sphincters, pinch the neck and keep urine in the bladder until you are ready to urinate.

The bladder neck and urethra are supported by the pelvic floor muscles. These muscles, which are shaped like a sling, attach to the spine in the back and the public bone in front, and keep your bladder, uterus and rectum in place. The position of these organs has a direct effect on the control of urine. Stretched and weakened pelvic floor muscles means these organs can shift and interfere with the functioning of your bladder.

Types of Incontinence

Urinary incontinence may be either transient (meaning it is temporary or reversible) or chronic (meaning it is long-term).

Transient Incontinence
Transient incontinence is usually related to an illness or a medical problem and disappears once the illness or problem is resolved. For example, urinary tract infections can cause bladder control problems. Certain medications, such as sedatives and diuretics, can also lead to urinary incontinence. If the incontinence experienced by a postmenopausal woman is caused by recurrent urinary tract infections, then taking a vaginal estrogen therapy may improve the symptoms associated with the incontinence.

Chronic Incontinence
Chronic incontinence is due to changes in the bladder and urethra or is the result of damaged pelvic muscles and nerves. Multiple pregnancies or aging can cause pelvic organs to shift and interfere with bladder function. Common types of chronic incontinence are the following:

1. Stress Incontinence

Stress incontinence is a common bladder control problem for women.

People with stress incontinence leak small amounts of urine when they cough, laugh, sneeze, rise from a chair, lift something or exercise. Stress incontinence may be described as minimal, moderate or severe. Minimal stress incontinence occurs only with vigorous activities, such as aerobics and sneezing. Occasional loss of urine after exercise or sneezing is nothing to be alarmed about. Moderate stress incontinence accompanies less vigorous activities, such as getting out of a chair or walking across a room. And severe incontinence occurs with almost any activity, such as changing position in bed.

Stress incontinence is caused by damaged or weakened urethral, sphincter or pelvic floor muscles. Pregnancy and vaginal childbirth can stretch and weaken pelvic floor muscles and damage the bladder neck. Hormonal changes that occur during menopause can also weaken the muscles and tissues in the pelvic floor, increasing the likelihood of stress incontinence. Other causes of stress incontinence include excessive weight, constipation, chronic cough, and rarely, nerve injury in the lower back.

2. Overactive Bladder

Overactive bladder is another common type of bladder problem.

People with overactive bladders need to urinate urgently and frequently, even when their bladders aren’t full. The urge to urinate can be so strong that they often leak moderate to large amounts of urine before they can get to the bathroom.

Overactive bladder occurs when the bladder's detrusor muscle contracts involuntarily. This may be due to nerve damage or an infection. Bladder nerves and muscles can also be harmed during surgery, or by conditions such as tumours, fibroids, Parkinson's disease, multiple sclerosis and stroke.

3. Mixed Incontinence

Many women have a combination of several types of incontinence. This is called mixed incontinence. The most common combination in women is stress incontinence and urge incontinence.

4. Overflow Incontinence

Overflow incontinence is less common than overactive bladder and stress incontinence. People with overflow incontinence dribble small amounts of urine frequently throughout the day. They may have trouble starting a stream of urine and once started, the stream is weak. They often feel that their bladder is never empty.

Overflow incontinence is caused when something blocks the urethra or when the bladder cannot properly contract, which causes the bladder to overfill. In women, the bladder may be blocked or narrowed by a prolapsed organ. Overflow incontinence can also be due to muscle or nerve problems that allow the bladder to overfill without sending the brain the message to urinate. Illnesses, such as diabetes, and medications, such as antidepressants or smooth muscle relaxants, may increase the capacity of the bladder, but can dull a person’s feeling that they need to urinate, which can result in overflow incontinence.


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  • A publication of:
  • Women's College Hospital